Method and tool for fastening connecting plates of a chain using connecting links

ABSTRACT

A method for fastening connecting plates of a chain with connecting links that are fabricated from an antifriction bearing steel 100Cr6. At least part of the connecting link is heated and is acted upon by a predetermined shaping force to attach a chain pin to the connection plate. The tool is in the form of a rotatable hard metal pin that is pressed with a predetermined pressing force against the connecting pin to be attached to the connecting plate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for fastening connecting plates of a chain by means of connecting links that are fabricated of an antifriction bearing steel 100Cr6. The invention also relates to a tool for fastening connecting plates of a chain by means of connecting links, in particular to carry out the method.

2. Description of the Related Art

Chains, in particular toothed chains or the like, are used principally in motor vehicle construction, in order to employ them as timing chains for camshafts or other components, for example. The chains normally have connecting plates, which are normally pivotably connected with each other by connecting links or connecting pins. The connecting pins are provided in openings of the connecting plates, the ends of the connecting pins being swaged or wedged over in order to attach them to the connecting plates.

In the known chains, the connecting links can be fabricated from steel, for example 39CrNoV13-9. That material is especially expensive. It is therefore also known to use an antifriction bearing steel 100Cr6 for the connecting links. That material has the disadvantage, however, that a connecting link made of it cannot readily be wedged over or fastened to the connecting plates, since the antifriction bearing steel can easily fracture due to its high brittleness. For that reason, the only possibility for a chain fabricated of that material is to fasten the connecting plates by means of friction welding or other complicated fastening methods. That is, however, likewise cost-intensive and complex due to the high heat generation.

Accordingly, an object of the present invention is to provide a method and a tool for attaching connecting plates of a chain by means of connecting links so that an especially economical chain can be produced.

SUMMARY OF THE INVENTION

That object is achieved with regard to methodology by a method for fastening connecting plates of a chain by means of connecting links that are fabricated of an antifriction bearing steel 100Cr6, where at least part of the connecting link is heated and is acted upon by a predetermined shaping force.

In that way, a connecting link made of the economical antifriction bearing steel 100Cr6 can be attached to the respective connecting plates without complicated attaching processes. Since the connecting plates that are not made of the antifriction bearing steel 100Cr6 are about 2.5 times as expensive as the connecting plates that are made of the antifriction bearing steel 100Cr6, an especially cost-effective chain can be manufactured by means of the method in accordance with the invention. The chain normally includes about 122 pins, so that a substantial savings potential can be realized. In addition, connecting links of antifriction bearing steel 100Cr6 are standard parts, so that there is the further advantage that no additional measures are necessary when fabricating different chains, since there is no danger of mixing the standard parts during manufacturing.

As part of an especially advantageous embodiment of the invention it can be provided that on a connecting link formed with a chain pin a rotating tool is applied to each end surface with a predetermined pressing force. Thus, in contrast to known methods no purely mechanical shaping is realized, in which the tool or the connecting link or the connecting plate is destroyed or damaged in the known method, but rather along with the applied shaping force heat is introduced into the connecting link or connecting pin due to the frictional heat that develops from the rotation of the tool. That combination of shaping force and introduction of heat enables non-destructive attachment of the chain pin to the connecting plate.

A possible configuration of that embodiment can provide for a hard metal pin to be used as the tool. Other materials and forms of the tool are also utilizable. It is important, however, that the tool have on the one hand adequate strength and on the other hand an appropriate coefficient of friction, so as to produce sufficient frictional heat in the part being attached, in addition to the application of shaping force.

It has been found that in the method in accordance with the invention rotational speeds of about 3000 to 4000 revolutions per minute are sufficient to realize optimal connection or attachment of the connecting pin to the connecting plate of the toothed chain. Other speeds are also possible, however, in particular if the dimensions of the tool are changed.

To enable optimal attachment of the chain pin to the connecting plate, the tool can be moved with a predetermined pressing force with its tip approximately perpendicular to the respective end surface of the chain pin. The both linear and rotary motion of the tool enables achievement of optimal swaging of the chain pin to the connecting plate of the chain. Preferably, two opposite portions of the edge area of each end surface of the chain pin, for example, are attached or swaged or wedged over by the tip of the tool. Other additional sections on the end surface of the chain pin can also be attached, however.

The object underlying the present invention is also achieved by a tool for attaching connecting plates of a chain by means of connecting links, in particular for carrying out the proposed method. The tool in accordance with the invention has a rotatable hard metal pin that can be pressed with a predetermined pressing force against the connecting link that is to be attached.

The tool in accordance with the invention can be utilized preferably to carry out the previously-described method to attach connecting plates of the chain by means of the connecting links formed with chain pins. Other possibilities for employment are also conceivable.

In accordance with a refinement of the invention, the hard metal pin can have a tip or the like with which an end surface of a chain pin designed as a connecting link can be shaped. Preferably, the hard metal pin can have a diameter of about 5 mm, with the hard metal pin being tapered so that the tip facing the chain pin has an end diameter of about 0.5 mm. Other dimensions are also possible, but the named dimensions have been found to be especially suitable, in particular with chain pins that likewise have a diameter of about 5 mm.

The tip of the tool can then be applied to the end surface of the chain pin with a predetermined pressing force to produce the necessary shaping force and with appropriate rotation, in order to realize the swaging or wedging over of the chain pin, at least in some sections.

In addition, in a next embodiment of the present invention the tool has a drive device or the like, with which the hard metal pin can be caused to rotate. The drive device can preferably effect a rotational speed of the hard metal pin of about 3000 to 4000 revolutions per minute. Other speeds of rotation can also be set.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic side view of a tool in accordance with the invention while attaching a connecting link to a chain (not shown);

FIG. 2 is a schematic top view of the attached connecting link; and

FIG. 3 is a schematic perspective view of a connecting plate with connecting pins attached to it.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an embodiment of a tool for attaching a connecting link to a connecting plate of a chain. The tool in accordance with the invention can be used preferably to carry out the method also proposed in accordance with the invention for attaching connecting plates of a chain by means of connecting links. The chain normally includes connecting plates 5, which are pivotally connected with each other flexibly by connecting pins, for example chain pins 2. The chain pins 2 are preferably fabricated of the inexpensive antifriction bearing steel 100Cr6.

In the embodiment shown, the tool includes a hard metal pin 1 that has a diameter of about 5 mm. The tip 3 of pin 1 facing the chain pin 2 has an end diameter D of about 0.5 mm. The hard metal pin can be set in rotation by a suitable drive device (not shown). The speed of rotation is between about 3000 and 4000 revolutions per minute, the rotation of the hard metal pin 1 being indicated by a curved arrow in FIG. 1.

In addition, the hard metal pin 1 can be moved in the axial direction relative to the chain pin 2. That is also indicated by an axially-directed arrow in FIG. 1. As a result, the hard metal pin 1 can be moved both linearly and rotationally relative to its longitudinal axis. Due to the linear motion, a predetermined axial pressing force of the hard metal pin 1 can be brought to bear on the upper end surface 4 a of the chain pin 2, which brings about a corresponding shaping force on the respective lower end surface 4 b of the chain pin 2.

In addition, due to the rotation of hard metal pin 1 frictional heat is produced at the upper end surface 4 a of chain pin 2, so that an introduction of heat into the respective end surface 4 a of chain pin 2 occurs. In that way, at least parts of chain pin 2 can be shaped by pressing force and the introduction of heat, in order to be attached to connecting plate 5.

The deformation of chain pin 2 is particularly visible in FIG. 2. In that embodiment, chain pin 2 is deformed at two opposing sections 6, 7 of the edge area of the end surface 4 b.

FIG. 3 shows as an example a connecting plate 5 with two chain pins 2, 2′ attached to it. Finally, chain pins 2, 2′ with the associated connecting plates 5 form an especially inexpensive chain, without any danger of components being destroyed during the attachment process.

Although particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. It is therefore intended to encompass within the appended claims all such changes and modifications that fall within the scope of the present invention. 

1. A method for connecting plates of a plate-link chain by connecting links, said method comprising the steps of: fabricating connecting links from antifriction bearing steel 100Cr6; and heating and applying a predetermined shaping force to at least part of the connecting link.
 2. A method in accordance with claim 1, including the steps of: providing a chain pin for joinder to a connecting plate; and applying a predetermined pressing force to each end surface of the chain pin with a rotating tool.
 3. A method in accordance with claim 2, wherein the rotating tool is a hard metal pin.
 4. A method in accordance with claim 2, including the step of rotating the tool at a speed of about 3000 to 4000 revolutions per minute.
 5. A method in accordance with claim 2, including the step of moving a tip surface of the tool against an end surface of the chain pin with a predetermined pressing force.
 6. A method in accordance with claim 5, including the step of deforming at least parts of an edge area of each end surface of the chain pin with the tip of the tool.
 7. A tool for attaching chain pins to chain connection links by rotary and linear movement of the tool against a chain pin, said tool comprising a rotatable hard metal pin for pressing with a predetermined pressing force against the chain pin to be attached to a connection link.
 8. A tool in accordance with claim 7, wherein the hard metal pin has a tip for deforming an end surface of a chain pin forming part of a connecting link.
 9. A tool in accordance with claim 7, wherein the hard metal pin has a diameter of about 5 mm.
 10. A tool in accordance with claim 8, wherein the tip that faces the chain pin has an outer end diameter of about 0.5 mm.
 11. A tool in accordance with claim 7, including a drive device with which the hard metal pin is driven at a rotational speed of about 3000 to 4000 revolutions per minute. 